1. Field
The present disclosure relates to a roller for an imaging apparatus, and an imaging apparatus including the roller.
2. Description of the Related Art
According to a charging mechanism of a general electrophotographic imaging apparatus, as illustrated in FIG. 1, after being charged by a charging roller 16, an image carrier 11 is exposed to light from a laser scanning unit (LSU) 18 so that a latent image is formed on the image carrier 11. Toner 14 is supplied to a developing roller 12 by a toner supplying roller 13. The toner 14 supplied on the developing roller 12 is made to be a uniform thin layer by a toner layer-regulating device 15 and at the same time is frictional-charged. The toner 14 regulated by the toner layer-regulating device 15 develops the electrostatic latent image on the image carrier 11 into a toner image, which is then transferred to paper by a transfer roller 19 and fixed by a fixing device (not shown). A cleaning blade 17 is used to remove the toner remaining on the image carrier 11 after the transfer.
As described above, imaging apparatuses employ functional rollers, such as, for example, a charging roller, a developing roller, a toner supply roller, and a transfer roller. These functional rollers are conventionally in the shape of shafts, and are made of metal. For example, SUM 22, SUS 416, and the like are widely used to manufacture the functional rollers. A pseudo-conductive rubber or foam part is fit to a metallic shaft with an adhesive applied around the metallic shaft. Vulcanization may be performed if necessary. The vulcanization process is typically performed at around 180° C., and thus materials with good heat resistance are suitable. For a polishing process to obtain a desired outer diameter, materials with high flexural strength are generally suitable. Therefore, resin alternatives to such metal materials need to have high conductivity, heat resistance, and mechanical strength. A metallic shaft (such as a Core Bar) is very expensive, and very heavy due to a large specific gravity. Furthermore, the more complicated the structure of its opposite ends, the much higher the cost of machining through cutting becomes. In general, metallic shafts are made of free-cutting steel plated with nickel (Ni) or zinc (An). However, when exposed to humid conditions for a long time, free-cutting steel becomes easily rusted. Thus, the free-cutting steel is often replaced with much more expensive materials such as stainless steel to avoid this problem.